Superficial siderosis due to dural defect with thoracic spinal cord herniation.

Superficial siderosis (SS) of the central nervous system is a rare disorder caused by chronic or recurrent hemorrhages into the subarachnoid space with hemosiderin and ferritin deposition, which leads to neuronal damage. The source of bleeding remains unknown in 50% of cases. Recently, attention has been focused on fluid-filled collection in the spinal canal, suggesting the presence of a dural defect which may be the bleeding point. We present a patient with SS and spinal extradural fluid collection due to midthoracic dural defect with spinal cord herniation. The reduction of the spinal cord herniation and the repair of the dural defect resulted in the disappearance of the fluid collection and cerebrospinal fluid abnormalities. The case here reported is, to our knowledge, the first case of spinal cord herniation presenting with SS and confirms the key role played by dural lacerations in the pathogenesis of both SS and spinal cord herniation. The search for dural lacerations should be one of the primary aims in patients with SS.